Most weather-radar precision performance is affected by the quality of the angular sensor (e.g., resolver) used to determine pointing accuracy of an antenna sensor oriented by one or more gimbals, for example, to which the antenna sensor is attached. FIG. 1 illustrates an exemplary dual-axis radar-scanning assembly 10. The assembly 10 includes a base member 20 supporting a first gimbal 30, which rotates about an axis x, and a second gimbal 40, which rotates about an axis y generally perpendicular to axis x. A frame 50, which is configured to support an antenna sensor (not shown in FIG. 1), may be mounted to the first gimbal 30, so as to be rotated in a two-dimensional scan field by the gimbals 30, 40. The assembly may include one or more resolvers (not shown in FIG. 1) functioning to provide signals indicating the angular position of the gimbals 30, 40.
As a consequence of the angular sensor used and its inherent precision, or lack thereof, the reported position has a defined amount of error associated with it. High-precision angular sensors are very costly and would impact the unit cost and marketability of the radar system. Moreover, simple calibration procedures, such as using a digital protractor, have been used to define the zero position (boresight) of a single-axis or multiple-axes antenna-gimbal assembly. This is a one-point calibration approach that typically does not provide a sufficient level of calibration accuracy. As such, it would be advantageous to use lower-cost sensors, with their typically lower-precision capability, with high-precision results.
One solution, as provided by U.S. Pat. No. 8,077,080, which is hereby incorporated by reference, uses a high-resolution calibration table with no specification that consecutive values in the table be sufficiently continuous. If a discontinuity of consecutive values in the table exists, the antenna control system may generate a large corrections causing high power consumption.